It is often desirable to provide fluid level instrument readout capability both locally, in proximity to the instrumented equipment, and at a remote location. In electric generating power plants and industrial applications, for example, boiler steam/water level readout is typically provided in the vicinity of the boiler drum and at a panel in a remotely located control room.
U.S. Pat. No. 4,397,182 discloses a fiber optic light conducting system that provides a steam/water level indication for boilers which have both a remote and local readout display of boiler steam/water level.
In that type of system, a plurality of tungsten filament lamps are used to generate light beams which are passed through side-by-side red and green filters. The colored light is focused onto and passed through transparent viewing ports of a boiler water level gauge and then through shutters and secondary focusing lenses which direct the beams through beam splitters. The beam splitters divide each of the beams into a major portion which is focused onto the polished input end of a fiber optic cable that transmits the major portion to the remote control room and a minor portion which is reflected to a locally mounted glass diffuser to provide a local indication of steam/water level. Although such a system may operate satisfactorily, the local readout necessitates an undesirable diversion of power from the fiber optic cable to the control room and is physically expensive to incorporate.